At the present time, many propulsion apparatus for use with a fluid and in particular, propeller assemblies for use in a liquid medium with marine engines, are constructed of a plurality of axially projecting blades. This conventional design has a number of drawbacks, not the least of which is that if one wishes to vary the direction of the propulsion, i.e. going from forward to reverse, it is necessary to provide a transmission between the motor and the propeller to reverse the rotation of the propeller thereby providing for reverse movement. This direct relationship between the engine and transmission is required to provide proper directional rotation of the propeller for maintenance of forward or reverse speeds and the degree of propeller thrust obtained. Axially mounted propellers when used with marine engines are also very susceptible to fouling up, especially in low draft waters with a weedy bottom and to damage if in contact with hard objects.
There thus remains a need for a propulsion apparatus for fluid medium which reduces the above disadvantages.
The present invention provides for a propulsion apparatus for fluid medium comprising an open-ended sleeve having an inlet and outlet for flow through of fluid and a series of cooperating blades positioned along the sleeve. Each of the blades has a leading and trailing edge and the blades are fixed to rotate with the sleeve and cause a progressive acceleration of fluid from the inlet to the outlet with rotation of the sleeve thereby providing thrust for propulsion. The blades cooperate to define a fluid path to accelerate a fluid from the inlet to the outlet to thereby provide thrust for propulsion as the sleeve is rotated.
In an aspect of the invention, the array of the blades is angularly adjustable to vary the bite of the blades from the perpendicular.
In another aspect of the invention, the leading and trailing edges of the blades are adjustable, thereby varying displacement of the fluid medium by the blades.
In yet another aspect of the invention, the adjustment of the pitch of the leading and trailing edges of the blades, in conjunction with the adjustment of the angular bite of the blade, allows for both forward or reverse thrust without reversal of the direction of the driving mechanism of the apparatus.
The apparatus of the present invention provides forward and reverse speed of propulsion independent of the speed of the driving mechanism whereby adjustment of the blades at a fixed speed accelerates or decelerates the propulsion effort.